Poly(trimethylene terephthalate) (“PTT”) and its use in many applications, including fibers, has been described in the literature. PTT is a polyester derived from terephthalic acid or an ester thereof and trimethylene glycol (also known as 1,3-propanediol) (“PDO”). The PDO may be prepared by various chemical or biochemical routes, including from various sugar sources such as corn, and thus can be prepared from a renewable resource. New PTT filaments having improved strength and stiffness (demonstrated by higher modulus) have been desired.
In addition, since terephthalic acid and its esters are presently prepared from petroleum base, it is desired to increase the green (renewable resource base) of PTT compositions without harming the overall properties of products.
Japanese Patent Publication No. 2003-041435 describes mixtures of PTT and 1-10 wt % of a polyester consisting essentially of polylactic acid. The mixtures are used to prepare hollow, crimped staple fibers. Poly(lactic acid) can also be prepared from a renewable resource, being prepared from lactic acid (2-hydroxypropionic acid) and its intermolecular esters that are in turn prepared from carbohydrates by lactic acid fermentation. Japanese Patent Publication No. 2003-041435 is focused on using polylactic acid to provide a more stable crimp.